//
//  UIBarButtonItem + Extension.swift
//  TWeibo
//
//  Created by wtw on 15/8/7.
//  Copyright © 2015年 wtw. All rights reserved.
//

import UIKit

extension UIBarButtonItem {

    //分类只能够提供便利构造函数，便利构造函数中，需要调用 self.init()
    convenience init(imageName: String,target: AnyObject?,action: String?) {
        let button = UIButton()
        button.setImage(UIImage(named: imageName), forState: UIControlState.Normal)
        button.setImage(UIImage(named: imageName + "_highlighted"), forState: UIControlState.Highlighted)
        button.sizeToFit()
        
        //设置监听方法，判断 action key 是否存在
        if let actionName = action {
            button.addTarget(target, action: Selector(actionName) , forControlEvents: UIControlEvents.TouchUpInside)
        }
        
        //调用指定的构造函数
        self.init(customView: button)
    }
}